This invention relates to an electric circuit for driving a piezoelectric vibrator. One type prior art transistor circuit is shown in FIG. 5 as an example of a conventional driving circuit for a piezoelectric vibrator.
In FIG. 5, when a transistor T.sub.r1 has been turned OFF at the trailing edge of each pulse depicted by a waveform A of FIG. 6, the piezoelectric vibrator P.sub.1 is applied with a damped oscillation voltage depicted by a waveform B of FIG. 6. The effective electric energy for driving the piezoelectric vibrator P, however, is contained only in the first pulse of narrow width of each repeating wave pattern. Consequently, it was hard to gain much driving force. For that reason, for instance, in case the driving circuit is used as a vibration source of a sound generator, it had a defect of being unable to produce a high sound pressure level.
It is known that if the number of turns in the winding of the coil L.sub.1 is increased, the sound pressure level will be increased. But as the number of turns is increased, the space occupied by the coil L.sub.1 is also expanded. Therefore, it is hard to adopt it to a small-sized device such as a small sized electronic alarm timepiece. In addition, though it may be possible to adopt a transformer as a driving circuit, such is undesirable in view of the space requirements.